Hyperthermia, particularly in combination with chemoradiotherapy, is widely used to treat various cancers. However, hyperthermia treatment is often insufficient due to thermo-tolerance. To date, the detailed mechanism underlying thermo-tolerance has not been clarified. The nuclear factor erythroid 2-related factor 2 (Nrf2)/ antioxidant response element (ARE) pathway is an important cellular cytoprotective defense system that is activated by various stresses. In this study, using immunocytochemistry and western blot analysis, we demonstrated that heat stress induced Nrf2/ARE activation through the nuclear translocation of Nrf2 in non-small cell lung cancer cells. Luciferase activity was also increased. Additionally, antioxidant enzymes were increased through Nrf2 activation after heat stress. Transfection of lung cancer cells with siRNA directed against Nrf2 increased heat cytotoxicity and cell apoptosis. Heat stress could induce reactive oxygen species (ROS) accumulation, while the antioxidant NAC obviously reduced cell apoptosis ratio, indicating that heat stress induced cell apoptosis in a ROS-dependent manner. Knockdown of Nrf2 led to an abnormal elevation of ROS, and the antioxidant NAC could increase Nrf2 activation, indicating that ROS and Nrf2 act within a negative feedback loop. Taken together, these results demonstrated that Nrf2 pathway is important for maintaining resistance to heat stress, and we postulated that Nrf2 may represent a potential therapeutic target for hyperthermia in lung cancer.

中文翻译：

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Nrf2 / ARE途径激活参与非小细胞肺癌细胞中负调控热诱导的凋亡。

热疗，特别是与放化疗结合使用，被广泛用于治疗各种癌症。然而，由于耐热性，高热治疗常常不足。迄今为止，耐热的基本机理尚未阐明。核因子类胡萝卜素2相关因子2（Nrf2）/抗氧化剂反应元件（ARE）途径是一种重要的细胞细胞保护防御系统，可被多种压力激活。在这项研究中，使用免疫细胞化学和蛋白质印迹分析，我们证明了热应激通过Nrf2在非小细胞肺癌细胞中的核易位诱导了Nrf2 / ARE激活。荧光素酶活性也增加。此外，抗氧化酶通过热应激后Nrf2激活而增加。用针对Nrf2的siRNA转染肺癌细胞会增加热细胞毒性和细胞凋亡。热应激可诱导活性氧（ROS）积累，而抗氧化剂NAC则明显降低细胞凋亡率，表明热应激以ROS依赖性方式诱导细胞凋亡。击倒Nrf2会导致ROS异常升高，而抗氧化剂NAC可以增加Nrf2的活化，表明ROS和Nrf2在负反馈回路中起作用。综上所述，这些结果表明Nrf2通路对于维持对热应激的抵抗力很重要，并且我们推测Nrf2可能代表了肺癌热疗的潜在治疗靶标。而抗氧化剂NAC明显降低了细胞凋亡率，表明热应激以ROS依赖性方式诱导细胞凋亡。击倒Nrf2会导致ROS异常升高，而抗氧化剂NAC可以增加Nrf2的活化，表明ROS和Nrf2在负反馈回路中起作用。综上所述，这些结果表明Nrf2通路对于维持对热应激的抵抗力很重要，并且我们推测Nrf2可能代表了肺癌热疗的潜在治疗靶标。而抗氧化剂NAC明显降低了细胞凋亡率，表明热应激以ROS依赖性方式诱导细胞凋亡。击倒Nrf2会导致ROS异常升高，而抗氧化剂NAC可以增加Nrf2的活化，表明ROS和Nrf2在负反馈回路中起作用。综上所述，这些结果表明Nrf2通路对于维持对热应激的抵抗力很重要，并且我们推测Nrf2可能代表了肺癌热疗的潜在治疗靶标。